Impervious Cover
Impervious cover, including all human-made structures such as homes, driveways, and parking lots, is associated with loss of watershed function and increased pollutant and sediment loading. Disturbance of sensitive areas like wetlands led the USDA Forest Service and TRPA to develop the Bailey land capability system in the early 1970s. The system assigned all land in the region to land capability classes ranging from 1 to 7, with capability 1 being the most environmentally fragile and sensitive to development. The Bailey system prohibits new development on all capability 1 through 3 parcels and restricts the amount of land coverage (i.e., pavement and building footprint) that can be placed on capability 4 through 7 parcels. Since the system’s adoption coverage has been removed from more sensitive areas, and new development focused on less sensitive areas. Parcel level verification of land capability class before development ensures that excess coverage is not added within a land capability class and removal of coverage from sensitive lands is facilitated by Environmental Improvement Program partners and the California and Nevada land banks through the Excess Coverage Mitigation Program.
Since adoption, there have been questions about the feasibility and cost-effectiveness of attainment of the coverage target for the most sensitive lands (1b). Attainment would require the unlikely removal and/or relocation of 8.3 percent of all impervious cover in the Region, including removal and buyout (with transfers or retirement) of large portions of existing private development (residential, tourist, commercial) in the Region’s communities.
Indicators
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| THRESHOLD CATEGORY REPORTING CATEGORY INDICATOR |
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The threshold evaluation assigns a status to an indicator relative to the adopted standard. As shown on the icon legend below, the background color of the reporting icon communicates the indicator “status” or estimate of current condition. For numerical standards, the status of an indicator is classified into “better” or “worse” categories based on the percent divergence of the current indicator value from the standard or interim target. For most indicators, the current value is taken directly from the value recorded in the most recent year. In some cases, the average value calculated from all data collected during the evaluation period is used. When an average value is used, it is noted and explained on the indicator evaluation page for that specific evaluation year.
Note: Thresholds reported as "Implemented" refer to thresholds that were adopted as policy guidance in the development of the Regional Plan. In these cases, the subject policies, ordinances, or environmental protections have been incorporated into the TRPA Regional Plan and TRPA Code of Ordinances.